Abstract:

Plant species change soil abiotic and biotic properties which in turn influence the performance of plants, leading to so-called “plant-soil feedbacks” (PSF). It is the prerequisite of plant-soil feedbacks that plant species can cause specific changes in soil microbial communities which are characterized by specialized soil pathogens and mutualists. Specialized microbes can have substantial effects on host plants, but likely do not influence the performance of non-host plants. PSF have been used to interpret ecological processes of different scales since the concept was proposed in the 1990s, such as succession, interspecific competition, biological invasion and effects of global changes on terrestrial ecosystems. In recent years, community ecologists and theoretical ecologists have started to integrate the research of PSF and community ecology, resulting in fundamental progress. In this review paper, we introduce soil microbe-mediated PSF and its implications for plant species coexistence, community structure and ecosystem functions. Classical PSF theory assumes that soil microbes can generate stabilizing process which promotes plant coexistence. However, recent studies show that soil microbes can also cause fitness difference between plant species which can influence species coexistence through equalizing process. Community ecologists predict that rare species have less negative or more positive PSF than abundant species, thereby leading to negative correlations between plant landscape abundance and PSF. However, empirical evidence demonstrates inconsistent patterns such as negative, positive and neutral correlations, and coevolution of plants and soil pathogens is key to reconcile these patterns. Soil microbes are also considered as a fundamental factor regulating succession. Dilution of soil microbial effects is a mechanism of positive plant diversity-productivity relationships. Specialist pathogens and mutualists accumulate in the soil of monocultures, but their negative and positive effects are diluted in multi-species mixtures, thereby increasing and decreasing biodiversity effects on productivity, respectively. We suggest three directions for future studies: empirical testing for specialization of plants and soil microbes, multi-dimensional species coexistence and eco-evolutionary dynamics in plant-soil feedbacks.

Key words: plant-soil feedback, species coexistence, community structure, ecosystem functioning, coevolution